The major goal of this project is to understand the control of enzyme formation in the pathway of arginine biosynthesis in escherichia coli. We have developed cell-free systems for the synthesis of two of these enzymes, acetylornithinase and argininosuccinase. As a source of DNA, transducing phages carrying the structural genes for these enzymes have been obtained. Using these systems we have begun purification of the arginine repressor protein. Future studies will include complete purification of the repressor, binding of the repressor to operator sites for various structural genes, nature of the corepressor and tests for repression at the level of transcription and translation of arginine genes. Additional studies are concerned with the biosynthesis and function of putrescine and spermidine. These polyamines are formed from areginine and ornithine. We have isolated and mapped mutants blocked at various stages of putrescine and spermidine synthesis.